The invention relates to a laundry mangle comprising at least one mangle roller, which is held by means of at least one supporting arm in a heatable trough, in a service position, in which the mangle roller and the trough assume by means of at least one adjusting means a moveable position relative to each other that defines an inlet and outlet side for the passage of laundry articles.
A laundry mangle is known from the PCT/WO 85/03313, where there are several mangle rollers arranged successively in series. Due to the adjustability of the respective mangle roller to the assigned trough, an approximately parallel, preferably coaxial positioning of the longitudinal axes of the roller and semi-rotary cylinder can be obtained, a feature that should guarantee a frictionless operation of the mangle. Furthermore, it is possible to swing the mangle roller completely into or out of the trough, in order to have unimpeded access to the trough, for example, for the purpose of removing the laundry articles that have become caught, cleaning and/or ventilation.
To this end, the ends of the bearing axle of the respective mangle roller can be rotated in a pair of supporting arms, which can be swung up and down by means of a working cylinder around a stationary bearing point. The bearing, which can be adjusted within a narrow range, in the form of a bearing point, in order to guarantee frictionless operation, is then set in such a manner that a coaxial service position between mangle roller and assigned trough is achieved as far as possible; a position that is then fixed in tire effective service position.
The friction generated in this service position that is set once, between the mangle roller and the surface of the trough and that should have as low a value as possible does not remain, however, uniform and constant during service. First, due to its torque the driven mangle roller has the tendency to move in the direction of the trough on the inlet side of the mangle, a state that reduces on the inlet side the distance between mangle roller and trough, thus resulting in raised frictional values at this point. Secondly, the friction on the trough surface changes in an irregular and unpredictable manner, for example due to nonuniform heating or during the introduction of laundry articles, which, of course, exhibit different sizes, thickness and also frictional values and, being dragged along by the roller surface so as to cause friction, are moved along the trough surface.
This frictional force thus generated leads especially in the inlet sided region of the mangle to a nonuniform and raised ironing pressure. At the same time the mangle performance drops, since the ironing pressure on the laundry outlet side of the mangle drops due to the corresponding increase in distance from the trough, thus not resulting in the thermal transfer required there, whereas in the inlet sided region said ironing pressure increases only insignificantly as the pressure increases. The high pressure on the inlet side results in an undesired high wear not only on the laundry articles but also on the roller lining applied on the surface of the mangle roller.
A mangle of the aforementioned class is known from the DD-PS 24 331, where the mangle roller and the trough assume by means of the adjusting means a moveable position relative to each other while the mangle is operating. On both sides the mangle roller is mounted on a supporting arm, by means of which it can be swung out; and simultaneously a drive wheel for the mangle roller is mounted on the swivel pin. Mangle roller and drive wheel are connected together by means of the meshing of a gear wheel. To eliminate the resulting tooth pressure, which leads to a nonuniform ironing or pressing pressure within the trough, the known rotary mangle provides that between the gearwheel of the roller axle that exhibits the same or approximately the same diameter, and the actual drive wheel on the supporting arm there is an intermediate wheel, which can also be swung out. Furthermore, a spring energy store engaging at the support arm is provided as the adjusting means. The addressed deleterious tooth pressure is, in fact, eliminated with this known mangle. Yet at the same time forces are generated that push the mangle roller on the inlet side against the trough and move away from said trough on the outlet side. The result is an increase in the frictional force and thus a nonuniform ironing pressure that is excessive on the inlet side with the aforementioned drawbacks.
In another mangle of this class according to the DE-OS I 813 594 the mangle roller is suspended rotatably from a supporting arm, which forms a rocking arm and which is attached in such a manner to a mangle housing that it slopes upward from the roller axle to the housing suspension, thus resulting in an angle ranging from 0.degree. to 90.degree. between the rocking arm and a horizontal line extended through the center point of the roller, when seen in the direction of rotation. The larger the angle is chosen, the greater is also the contact force of the roller on the trough, and the greater is the frictional force between the mangle roller and the trough. Not to exceed at this stage a deleterious maximum frictional value as the strength of the laundry articles increases, the trough can be swivelled flexibly by means of adjusting means as a spring energy store. With this known laundry mangle the resulting frictional force can be compensated for only partially and in particular the ironing pressure cannot be set either constantly or increasingly in the direction of the outlet side.
In another kind of known laundry mangle of this class according to the DE-AS 1 211 122 the mangle roller is pivot-mounted on supporting arms by means of one pair and enveloped in the swung-in state stationarily by an ironing trough, which is designed as a half shell and whose fee ends are driven by means of a mechanical device or with a heating medium in such a manner that they move toward each other during service in order to increase the ironing pressure, thus reducing on the inlet and outlet side the distance between mangle roller and trough. In addition, to decrease the pressing pressure the mangle roller can be simultaneously lifted by means of the two supporting arms, With this known mangle roller the ironing pressure for the laundry articles can be increased on the inlet and outlet side, so that at these points altogether high frictional values with the drawbacks described above are generated. In contrast, the frictional values drop in the center of the trough and the ironing pressure decreases dramatically, so that altogether the mangle output of this known mangle is low.
Starting from this prior art, the invention is based on the problem of providing a laundry mangle, where the described drawbacks are avoided. This problem is solved by a laundry mangle exhibiting the combined features of claim 1.
Since, according to the invention, a force, which counter-acts in such a manner the frictional force generated during service of the laundry mangle that the ironing pressure is constant or increases in the direction of the outlet side, is exerted by means of the respective adjusting means on the mangle roller and/or the trough, which assumes during service a moveable position relative to each other, a dynamic adaptation of the position of the mangle roller and the trough to each other during service of the laundry mangle is achieved, during which service the force compensating for the frictional force increases or decreases, depending on whether the frictional force acting between the mangle roller and the trough increases or decreases. In so doing, first the distance between the mangle roller and the trough increases in principle on the inlet side and then decreases on the outlet side during service of the mangle.
Thus, an undesired increase in the ironing pressure in the feed sided region of the mangle is reliably avoided. Rather the compressive load per unit area remains constant or increases in the direction of the outlet side along the entire ironing gap, formed between mangle roller and trough. This allows a careful pressing of the laundry and the wear is low, especially at the roller lining. Size and direction of the frictional force and thus the compensating force result from the contact pressure and direction of rotation of the roller. Within the scope of the invention it is basically irrelevant whether the roller is braced moveably with respect to the roller, attached stationarily with its bearing axle, against the compensating force of the force-generating device, according to the application for protection.
Provided the respective adjusting means act in such a manner that the ironing or pressing pressure increases constantly in the direction of the outlet side, increased mangling output can be obtained. Owing to the relatively high temperature difference between the laundry articles, introduced on the feed side, and the heating temperature in the ironing gap there, no improved drying results can be obtained any more even with relatively high ironing pressures. However, this state improves if the temperature differential decreases following passage through the respective trough. If then a correspondingly high ironing pressure is generated on the outlet side, the result on average is significantly improved thermal transmission coefficients. If viewed from the point of view of total energy, in the laundry mangle designed to this end, the mangle output compared to a laundry mangle with constant ironing pressure is definitely raised over the entire trough surface, without resulting, however, in a wear of the laundry articles and/or the mangle. For the following troughs the mangle output, can be optimized to the effect that for a roller, which follows immediately in the conveying direction and exhibiting a trough, a uniform ironing pressure is set by means of the adjusting means; and for the roller that follows last and exhibits a trough the ironing pressure is set so as to decrease in the direction of the output side. The mangle roller arranged last when seen in the conveying direction discharges the already dried laundry articles, without any unnecessary overheating, damaging the laundry articles, on the outlet side. These embodiments make it clear that with suitable adjustment of the setting means for the laundry mangle according to the invention, the conventional design of a laundry mangle can also be realized, provided it seems expedient with regard to energy considerations. Thus, with the laundry mangle according to the invention, a wide band range of possible operating modes for a mangling process of laundry articles can be realized, without necessitating any significant structural modifications.
In an especially preferred embodiment of the laundry mangle according to the invention, two working cylinders are provided, of which one absorbs the gear-sided driving torque. On the basis of this arrangement a uniform ironing pressure within the trough can be generated with two identical working cylinders when the lever arm is shortened on the socalled exhaust air side of the laundry mangle, a feature that can lower the production costs of the laundry mangle according to the invention.
Other preferred embodiments of the invention are the subject matter of the dependent claims.